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This Week in PLOS: Jul 20, 2015

In PLOS Genetics, researchers from the US and Italy illustrate applications of newly designed software that takes into account sequencing error and allele variation to assess mitochondrial sequence variants and mitochondrial DNA copy numbers from whole-genome sequence data. The team demonstrated the reliability of this scheme using lymphocyte cell sequences from some 2,000 Sardinian individuals, uncovering examples heritability patterns and age-related surges in heteroplasmic mtDNA sequences. "To our knowledge, this is the largest population analysis to date of mtDNA dynamics," the authors write, "revealing the age-imposed increase in heteroplasmy, the relatively high heritability of copy number, and the association of copy number with metabolic traits."

A Palestinian team used a technique dubbed Copro-PCR to look at the prevalence of the hydatidosis-causing parasite Echinococcus granulosus in dogs — a strategy they describe in PLOS Neglected Tropical Diseases. After isolating genomic DNA in fecal samples from 93 domestic dogs tested in three regions where human E. granulosus infection following surgery is relatively high, the researchers amplified portions of the E. granulosus genome by PCR, picking up on the presence of the parasite in a larger than expected proportion of dogs. Based on these and other findings, the study's authors argue that there is "strong evidence of ongoing infection events in the definitive [E. granulosus] host which poses a great risk to humans."

A PLOS One paper by researchers in the UK and Malawi traces tuberculosis transmission patterns in Malawi with the help of whole-genome sequencing. Based on variants in Mycobacterium tuberculosis isolates from 187 index tuberculosis cases in the Karonga district and one or more infected contact per person, the team concluded that transmission of the disease between known contacts from the same household accounted was relatively rare, accounting for fewer than 10 percent of the cases. In the tuberculosis-endemic region considered, the study's authors note that "even those with a family contact with smear positive tuberculosis are likely to have acquired their tuberculosis elsewhere."